Building Handrails for a Wooden Deck

When building handrails for a wood deck, make sure to check your local building codes first to find out the acceptable railing height, space between balusters, and distance between posts that is required.

While building codes can vary, most building codes require:

  • 6’ or less between posts.
  • 36” or higher handrails.
  • 4” or less opening between balusters.

Materials needed for a 6′ section of railing:

  • Rail cap: 1 – 5/4” x 6” x 6’
  • Top and bottom rails: 2 – 2” x 4” x 6’
  • Balusters: 13 – 2” x 2” x 32”

Building Deck Handrails

The railings are constructed with the bottom rail on edge to resist sagging, and the top rail horizontal to provide lateral strength.

  • Cut the top and bottom rails so they fit snugly between the posts.
  • Cut the balusters to length with the end cut square on the top and at a 45° angle on the bottom.
  • Mark the location of the balusters on both the top and bottom rails.
  • Use deck screws to attach the bottom of the balusters to the face of the bottom rail so the angled cut on the baluster is flush with the bottom of the rail.
  • Attach the top of the balusters through the top rail.
  • Stand the section of railing up and attach the top rail flush with the top of the posts.
  • Attach the bottom rail between the posts.
  • Miter the rail caps where they meet at corners and join together.
  • Attach the rail caps to the top of the posts and top rails.
  • Attach a block between the deck and bottom rail in the center of the span to provide added support.


Watch this video to learn more.

Further Information

Danny Lipford: Once you’ve completed installing deck boards on your deck, you’ll want to add handrails. We’re using our deck foundation posts for the rail posts, so they have to be cut off at a uniform height above the deck.

In this case our rail will be 36 inches above the deck, which is common for most residential decks. Because building codes often vary, you should check with a local building department before you make that decision.

The rails we’re building include three components: two-by-fours for the top and bottom rails, two-by-twos for the balusters, and five-quarter-by-six deck boards for the rail caps. The bottom rail is positioned vertically to prevent sagging, and the top rail horizontally to provide lateral strength.

The two-by-two balusters are cut square on the top and diagonally on a 45-degree angle on the bottom. The gap between the balusters should be less than four inches, so installing them on five-inch centers will work with these two-by-twos, which are one-and-a-half-inch thick.

We’re using deck screws to assemble the rails so there’s no chance of loose nails later on. After each section is assembled on the deck, we stand them up and attach them to the posts. The top rail is lined up with either edge and flush with the top of the post. Driving the screws into the post at an angle, or “toe-screwing,” is the best way to attach them.

The bottom rail is inset one-inch from the outer edge of the post. The last step is to install the five-quarter rail cap, which is centered over the posts. For longer runs you may also need to join these boards at a 45-degree angle cut. It’s best to do this over a post if possible. You’ll also want to make 45-degree miter cuts wherever the rails caps join in a corner.


  1. The math doesn’t add up on the bottom of these handrails, if you inset the bottom rail 1″ then add the 1 1/2 inch of the bottom rail then the 1 1/2 inch of the spindle that is 4″. Your spindles will be sticking out 1/2″ at the bottom and flush at the top.

    To make them flush with the posts you would have to inset the rial 1/2″ at the bottom and screw the spindles flush with the top rail, not in the center.

  2. I love how the attachment of the top rail is shown and explained in some detail but the attachment of the bottom rail: not at all.

  3. Currently building a deck and saw this in the nick of time! Good to know that the top and bottom of the handrails need to fit snuggly between the posts. My brother’s also about to tackle a deck project and I’ll share this information with him so that he can look into his options.


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